16.8.3.1 Identification
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Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Low active power and power factor
protection
LAPPGAPC
- 37_55
16.8.3.2 Application
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Low active power and power factor protection (LAPPGAPC) is one of the local
criteria to be checked in direct transfer trip (DTT) scheme. In LAPPGAPC, active
power and power factor are calculated from the voltage and current values at this
end. On detection of low active power or low power factor condition, the trip
output will be set. All the calculation and comparison are done per phase.
If there is a fault and the remote end circuit breaker is tripped, a carrier signal is
sent to the local end and the active power in respective phases will decrease.
Hence, detection of low active power in at least one of the phases would be one of
the factors to ascertain the fault at other end.
The function has two modes, '1 out of 3' and '2 out of 3'. '1 out of 3' mode ensures
that there is low active power in at least one of the three phases, while the '2 out of
3' mode the low power is ensured in at least two phases simultaneously before
sending the trip signal.
Line which is tripped at the remote end will have low active power flowing through
it which also results in low power factor in the respective phase. A low power
factor criterion could also be an added check of the local criterion in DTT. In this
function phase wise power factor is calculated, and a comparison is made for the
low power factor condition to give phase segregated start and trip.
16.8.3.3 Setting guidelines
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GlobalBaseSel: Selects the global base value group used by the function to define
IBase, UBase and SBase as applicable.
OperationLAP: Used to set the low power function On or Off.
OpMode: Can be set 2 out of 3 or 1 out of 3. If 1 out of 3 is set, the function will
send TRIP signal if one or more phases have low power. If 2 out of 3 is set, the
function will send TRIP signal if two or more phases have low power. When the
remote breaker has opened, there should theoretically be zero power at the
protection measurement point. However, when fault current is fed to the fault point
the power loss in the fault will be detected. For operation for all unsymmetrical
faults 1 out of 3 should be selected.
1MRK 506 369-UEN B Section 16
Scheme communication
Line distance protection REL670 2.2 IEC 729
Application manual
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